Electron microscope specimen stage which maintains specimen position when subjected to thermal fluctuations

ABSTRACT

An apparatus comprising two cooperating levers for adjusting the position of an object about a standard axis within a container such as an electron microscope such that the object will not be displaced from the axis on thermal expansion or contraction of the container or apparatus.

United States Patent Inventor Shigeru Suzuki Tokyo, Japan Appl. No. 879,887 Filed Nov. 25, 1969 Patented Oct. 12, 1971 Assignee Nihon Denshi Kabushiki Kaisha Tokyo, Japan Priority Nov. 29, 1968 Japan 43-87478 ELECTRON MICROSCOPE SPECIMEN STAGE WHICH MAINTAINS SPECIMEN POSITION WHEN SUBJECTED TO THERMAL FLUCTUATIONS 3 Claims, 11 Drawing Figs.

U.S. Cl 250/495 B, 5,0/49.5.

[51] Int. Cl H0lj 37/20 [50] Field of Search... 250/495 B Primary Examiner-James W. Lawrence Assistant Examiner-C. E. Church Attorney-Webb, Burden, Robinson & Webb ABSTRACT: An apparatus comprising two cooperating levers for adjusting the position of an object about a standard axis within a container such as an electron microscope such that the object will not be displaced from the axis on thermal expansion or contraction of the container or apparatus.

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BY I (UM ,MM .W IMO ELECTRON MICROSCOPE SPECIMEN STAGE WHICH MAINTAINS SPECIMEN POSITION WHEN SUBJECTED TO THERMAL FLUCTUATIONS BACKGROUND This invention relates to an apparatus for adjusting an object positioned within a vacuum chamber, for example, an electron microscope. Prior art devices, such as are described in U.S. Pat. No. 2,410,658 and German Pat. No. 1,018,563, comprise a rigid supporting member which is pivotally secured to the walls of the electron microscope in order to facilitate adjustment of the position of the object, for example, the specimen or diaphragms. Thermal expansion or contraction of the container results in a shift thereof away from or toward the optical or X-ray axis. Hence, variations in atmospheric temperatures surrounding the electron microscope result in a displacement of the specimen or diaphragm held by the supporting member away from the optical axis; A displacement will also occur when the supporting member itself expands or contracts on heating or cooling which may be caused by a specimen heating device or by electron beam irradiation of the supporting member. It is an advantage of apparatus according to this invention that an object may be positioned along a standard axis such as an optical axis within a container such as a column of an electron microscope whereby heating and cooling of the apparatus of the container will not cause a displacement of the object away from the standard axis.

BRIEF DESCRIPTION Briefly, this invention comprises an apparatus for adjusting the position of an object about a standard axis within a container, such as an electron microscope vacuum chamber, comprising two cooperating levers pivotally secured relative to the container walls. The first lever has an object holder in one end extending over the standard axis. The object end of the first lever is moveable or shiftable in a plane containing the standard axis and is biased away from the container walls. The second lever makes slideable contact with a contact face on the object end of the first lever. The levers are rotated by adjusting devices such as thumbscrews that slideably abut contact faces on the levers. By rotating the levers the object may be positioned about the standard axis within a plane perpendicular to the standard axis. All of the contact faces lie in planes which contain the standard axis and the elongate axis of one of the levers as an element. In this way, thermal expansion of the container or the levers does not affect the position of the object relative to the standard axis.

DETAILED DESCRIPTION Further features and other objects and advantages of this invention will become apparent from the following detailed description made with reference to the drawings in which:

FIG. I is a plane sectional view showing one embodiment of the present invention;

FIG. 2 is a sectional view of FIG. 1 taken along the line A A;

FIG. 3 is a plane sectional view showing another embodiment of the present invention;

FIG. 4 is a sectional view of FIG. 3 taken along the line B B; and

FIGS. 5 and 6 show details of the contacting faces according to various embodiments of the present invention.

Referring to FIGS. 1 and 2, an apparatus for adjusting an object about a standard axis is secured within the walls 1 of a column or container such as the vacuum chamber of an electron microscope. Basically, the apparatus comprises a first lever 8 and second lever 17 which preferably form an angle of approximately 90 with each other but which may form an angle of substantially greater than or lesser than 90. The levers are pivotally secured relative to the walls 1, for example, through housings I2 and 19 which may be secured to the walls through a flange 2 on the housings. In accordance with a preferred embodiment of this invention, the first lever comprises a holder 3 having an orifice or specimen holder 4 positionable over the optical axis. A contact face 5 on the holder is disposed along a plane including the optical axis and the axis of the second lever 17. A spindle 6 secured to the holder 3 and having axis common with the holder is slideably positioned within a bore in lever 8. The bore has an axis common with the lever 8. A stop plate 7 is secured to the end of the spindle within the space 10 arresting the motion of the spindle relative to the lever. A spring 11 biases the holder 3 away from the lever 8. The lever 8 is pivotally secured at 13 by a pin which is substantially parallel to the optical axis and intersects the elongate axis of the lever 8 or is just slightly offset therefrom. At the end of the lever 8 opposite the bore, there is contact face 9 which lies in a plane including the optical axis as an element and the elongate axis of the lever 8 as an element. Thumbscrew 14 makes slideable contact with the contact face 9 of the lever 8 causing rotation thereof. Spring 15 biases the lever 8 against the thumbscrew 14.

Second lever 17 is pivotally secured at 18 by apin that is substantially parallel to the optical axis and intersects the elongate axisof the lever 17 or is just slightly offset therefrom. An operating part 16 forming part of the second lever abuts the face 5 of the holder 3. The second lever 17 has a contact face 20 which lies in a plane which contains the optical axis and the elongate axis of the second lever. Thumbscrew 21 is in slideable contact with the contact face and may be adjusted to cause rotation of the second lever. Spring 22 biases the second lever against the thumbscrew 21. g

The operation of the adjusting device according to this invention is as follows: The face 20 of the second lever I7 is pushed by turning the thumbscrew 21. As a result, the second lever 17 is rotated in the clockwise direction with respect to the pin 18 as its pivot center causing the face 5 of the holder 3 to be perpendicularly pushed by the operating part 16 of the second lever 17 which in turn moves the holder 3 and the object or orifice 4 in the right direction with respect to the drawings along the X-axis On the other hand, the face 9 of the first lever 8 is pushed by turning the thumbscrew 14. This causes the first lever 8 to rotate in such a way that since the spindle 6 and the lever 8 are unified the holder is shifted downward with reference to the drawings. In other words, the face 5 of the holder 3 moves along the Y-axis and in doing so causes the said face 5 to slide with respect to the operating part 16. Consequently, by suitably manipulating the screws 14 and 21, the orifice 4 can be adjusted along the X- and Y-axes.

Thermal expansion of the adjusting apparatus or of thewalls of the container to which it is secured will not cause a shift of the specimen or orifice 4 away from the optical axis. If the walls of the column 1 of the vacuum chamber expand or contract due to the variation in ambient temperature, the housings 12 and I9 shift along the X-axis and/or Y-axis respectively. The second lever 17 shifts along with the shift of the housing 19 but the operating part 16 of said second lever slides with respect to the face 5 of the holder 3. Consequently, the holder and the specimen or orifice 4 is not displaced. Moreover, if the lever 8 shifts with the shift in the housing 12, the lever will slide only with respect to the spindle 6. This is because the spindle 6 is mounted on the holder 3 and the lever 8 are mutually and slideably moveable along the X-axis and the holder 3 is biased by the spring 11 against the lever 17. Hence, the shift of the specimen or orifice 4 due to the thermal expansion or contraction of the walls 1 of the column is eliminated.

Furthermore, even an expansion of the first and second levers themselves will not cause displacement of the specimen or orifice 4 from the optical axis. As is apparent from the foregoing description, since the holder itself is positioned by the operating part 16 of the lever 17, the expansion or contraction of the lever 8 does not affect the shift of the holder along the Xaxis. Since the operating part 16 shifts only along the Y-axis when the lever 17 expands or contracts the holder is not caused to shift.

relative motion between the spindle and the lever 8. Neither of 5 these motions will cause a movement of the orifice or specimen 4.

FIGS. 3 and 4 show another embodiment of the present invention whereby the first lever is unitary. A pin 23 mounted on the lever 8 is positioned to slideably move within a groove 24 in housing 12. A tension spring 25 urges the second lever 17 against the object end 26 of the first lever 8 maintaining both levers in contact.

FIG. 5 shows four further embodiments of the present invention with reference to the connecting part of the holder 3 and the operating part 16 of the second lever 17. In FIG. 5(a) the holder 3 is provided with a toothed protrusion, and the second lever 17 is plain. In FIG. 5(b) a ball or roller 27 is arranged between the face 5 of the holder 3 and the plain surface (asillustrated in (a)) of the second lever 17. In FIG. 5(0) the said ball or roller 27 is inserted between a groove or indent 28 arranged in the second lever 17 and the face 5 of the holder 3. It is also possible to use a pin 3a in lieu of the said face 5 as shown in FIG. 5(d).

FIG. 6 shows three embodiments of the present invention with reference to the connecting part of the screw 14 and the face 9 of the lever 8. In FIG. 6(a) the face 9 of the lever 8 is provided with a toothed protrusion which makes contact with a plate 30 mounted on the screw 14. In FIG. 6(b) a rod 31 having one end of which is designed so as to form a curved face, is arranged so as to make contact with a curved face 33 of a lever 8. It is also possible to operate the lever 8 by means of a device comprising a rod 35, a lever 36 and a screw 37 as shown in FIG. 6(0).

It should be understood that throughout the specification and claims hereof, the contacting surfaces of said faces (5, 9 and 20) and the surface of the operating part 16 have been described for simplicity as being in special planes containing the standard axis and the elongate axis of a lever. Of course, the surface may be somewhat offset from or at a small angle with these special planes. Furthermore, it should be understood that these surfaces need not be planar but may have the various shapes, for example, described with reference to FIGS. 5 and 6. 1

Having thus described my invention in detail and with the particularity required by the patent law, what is desired protected by Letters Patent is set forth in the following claims. I claim:

1. An apparatus secured to the walls (1) of a vacuum container of an electron microscope for positioning an object about a standard axis comprising:

A. first lever (8) having an object end positioned over the standard axis, said lever having an elongate axis intersecting the said standard axis and being perpendicular thereto, means (13, 23) for pivotally securing the first lever relative to said container walls, said first lever having a first contacting surface (9) in a plane containing the standard axis and the elongate axis of the first lever as elements, said first lever having a second contacting surface (S) in a plane having the standard axis as an element, means (6, 24) for permitting translation of the object end of the first lever toward and away from the standard axis;

B. a second lever (17) having an elongate axis intersecting the standard axis and being parallel to the second contacting surface of said first lever, means (18) for pivotally securing said second lever relative to said container wall, said second lever having a means (16) at one end for slideably contacting the second contacting face on the first lever, said second lever having a contacting surface (20) in a plane containing the elongate axis of the second lever and the standard axis as elements;

C. a first adjustment means (14) slideably contacting the second contacting face (9) of the first lever and extending perpendicular therefrom for positioning said face;

D. a first biasing means (15) for urging the first lever against the first adjusting means;

E. a second adjusting means (21) slideably contacting the contacting face (20) of the second lever and extending perpendicular therefrom for positioning said face;

F. a second biasing means (22) for urging the second lever against the second adjusting means; and

G. a third biasing means (11, 25) for urging the object end of the first lever against the second lever.

2. An apparatus secured to the walls (1) of a vacuum container of an electron microscope for positioning an object about a standard axis comprising:

A. a first extendable lever (8) having a holder (3) positioned over the standard axis, said lever having an elongate axis intersecting the said standard axis and being perpendicular thereto, means (13) parallel to said standard axis aligned with the elongate axis for pivotally securing the first lever relative to said container walls, said first lever having a first contacting surface (9) in a plane containing the standard axis and the elongate axis of the first lever as elements, said holder having a second contacting surface (5) in a plane having the standard axis as an element and being perpendicular to the elongate axis of the first lever, means (6) for permitting movement of the holder (3) relative to the first lever (8) along the elongate axis of the first lever;

B. a second lever (17) having an elongate axis intersecting the standard axis and being parallel to the second contacting surface of the said first lever, means (18) parallel to said standard axis and aligned with said elongate axis for pivotally securing said second lever relative to said container wall, said second lever having a means (16) at one end for slideably contacting the second contacting face (5) on the holder, the surface of said contacting means being in a plane containing the elongate axis of the second lever, said second lever having a contacting face (20) in a plane containing the elongate axis of the second lever and the standard axis as elements;

C. a first adjustment means (14) slideably contacting the second contacting face (9) of the first lever and extending perpendicular thereto for positioning said face;

D. a first biasing means (15) for urging the first lever against the first adjusting means;

E. a second adjusting means (21) slideably contacting the contacting face (20) of the second lever and extending perpendicular therefrom for positioning said face;

F. a second biasing means (22) for urging the second lever against the second adjusting means; and

G. a third biasing means for urging the holder against the second lever.

3. An apparatus secured to the walls (1) of a vacuum container of an electron microscope for positioning an object about a standard axis comprising:

A. a first lever (8) having an object end positioned over the standard axis, said lever having an elongate axis intersect ing the said standard axis and being perpendicular thereto, means (23) parallel to said standard axis aligned with the elongate axis for pivotally and slideably securing the first lever relative to said container walls such that the first lever can rotate and slide parallel to a plane intersecting the standard axis, said first lever having a first contacting surface (9) in a plane containing the standard axis and the elongate axis of the first lever as elements, said first lever having a second contacting surface (5) in a plane having the standard axis as an element;

8. a second lever (17) having an elongate axis intersecting the standard axis and being parallel to the second contacting surface of said first lever, means (18) parallel to said standard axis and aligned with said elongate axis for pivotally securing said second lever relative to said container wall, said second lever having a means (16) at one end for slideably contacting the second contacting face (5) on the first lever, the surface of said contacting means being in a plane containing the elongate axis of the E. a second adjusting means (21) slideably contacting the contacting face (20) of the second lever and extending perpendicular therefrom for positioning said face;

F. a second biasing means (22) for urging the second lever against the second adjusting means; and

G. a third biasing means for urging the first lever against the second lever. 

1. An apparatus secured to the walls (1) of a vacuum container of an electron microscope for positioning an object about a standard axis comprising: A. first lever (8) having an object end positioned over the standard axis, said lever having an elongate axis intersecting the said standard axis and being perpendicular thereto, means (13, 23) for pivotally securing the first lever relative to said container walls, said first lever having a first contacting surface (9) in a plane containing the standard axis and the elongate axis of the first lever as elements, said first lever having a second contacting surface (5) in a plane having the standard axis as an element, means (6, 24) for permitting translation of the object end of the first lever toward and away from the standard axis; B. a second lever (17) having an elongate axis intersecting the standard axis and being parallel to the second contacting surface of said first lever, means (18) for pivotally securing said second lever relative to said container wall, said second lever having a means (16) at one end for slideably contacting the second contacting face on the first lever, said second lever having a contacting surface (20) in a plane containing the elongate axis of the second lever and the standard axis as elements; C. a first adjustment means (14) slideably contacting the second contacting face (9) of the first lever and extending perpendicular therefrom for positioning said face; D. a first biasing means (15) for urging the first lever against the first adjusting means; E. a second adjusting means (21) slideably contacting the contacting face (20) of the second lever and extending perpendicular therefrom for positioning said face; F. a second biasing means (22) for urging the second lever against the second adjusting means; and G. a third biasing means (11, 25) for urging the object end of the first lever against the second lever.
 2. An apparatus secured to the walls (1) of a vacuum container of an electron microscope for positioning an object about a standard axis comprising: A. a first extendable lever (8) having a holder (3) positioned over the standard axis, said lever having an elongate axis intersecting the said standard axis and being perpendicular thereto, means (13) parallel to said standard axis aligned with the elongate axis for pivotally securing the first lever relative to said container walls, said first lever having a first contacting surface (9) in a plane containing the standard axis and the elongate axis of the first lever as elements, said holder having a second contacting surface (5) in a plane having the standard axis as an element and being perpendicular to the elongate axis of the first lever, means (6) for permitting movement of the holder (3) relative to the first lever (8) along the elongate axis of the first lever; B. a second lever (17) having an elongate axis intersecting the standard axis and being parallel to the second contacting surface of the said first lever, means (18) parallel to said standard axis and aligned with said elongate axis for pivotally securing said second lever relative to said container wall, said second lever having a means (16) at one end for slideably contacting the second contacting face (5) on the holder, the surface of said contacting means being in a plane containing the elongate axis of the second lever, said second lever having a contacting face (20) in a plane containing the elongate axis of the second lever and the standard axis as elements; C. a first adjustment means (14) slideably contacting the second contacting face (9) of the first lever and extending perpendicular thereto for positioning said face; D. a first biasing means (15) for urging the first lever against the first adjusting means; E. a second adjusting means (21) slideably contacting the contacting face (20) of the second lever and extending perpendicular therefrom for positioning said face; F. a second biasing means (22) for urging the second lever against the second adjusting means; and G. a third biasing means for urging the holder against the second lever.
 3. An apparatus secured to the walls (1) of a vacuum container of an electron microscope for positioning an object about a Standard axis comprising: A. a first lever (8) having an object end positioned over the standard axis, said lever having an elongate axis intersecting the said standard axis and being perpendicular thereto, means (23) parallel to said standard axis aligned with the elongate axis for pivotally and slideably securing the first lever relative to said container walls such that the first lever can rotate and slide parallel to a plane intersecting the standard axis, said first lever having a first contacting surface (9) in a plane containing the standard axis and the elongate axis of the first lever as elements, said first lever having a second contacting surface (5) in a plane having the standard axis as an element; B. a second lever (17) having an elongate axis intersecting the standard axis and being parallel to the second contacting surface of said first lever, means (18) parallel to said standard axis and aligned with said elongate axis for pivotally securing said second lever relative to said container wall, said second lever having a means (16) at one end for slideably contacting the second contacting face (5) on the first lever, the surface of said contacting means being in a plane containing the elongate axis of the second lever, said second lever having a contacting face (20) in a plane containing the elongate axis of the second lever and the standard axis as elements; C. a first adjustment means (14) slideably contacting the second contacting face (9) of the first lever and extending perpendicular thereto for positioning said face; D. a first biasing means (15) for urging the first lever against the first adjusting means; E. a second adjusting means (21) slideably contacting the contacting face (20) of the second lever and extending perpendicular therefrom for positioning said face; F. a second biasing means (22) for urging the second lever against the second adjusting means; and G. a third biasing means for urging the first lever against the second lever. 